The invention relates to a filler pipe for the fuel tank of a motor vehicle having an internally located closure flap which closes a filling aperture at the end region of an internally located housing part made from plastic and can be brought into its open position by means of the fuel-pump nozzle in order to fill the fuel tank, an elastomeric seal arranged on the housing part acting between the housing part and the closure flap.
Filler pipe for fuel tanks of motor vehicles are known, for example, in WO 99/03 697. The closure of this filler pipe is formed by an internally located closure flap. Therefore, in contrast to the customary designs otherwise in general use, no outer tank closure that can be screwed on or locked by means of a bayonet closure or the like is provided. Accordingly, the liquid- and gas-tight seal between the fuel tank on the one hand and the outer environment on the other is to be ensured by the valve closure. The housing part which, at its end region, forms the filling aperture to be closed by the closure flap is one of those components of the filler pipe that are made from plastic. It has proved inconvenient here that this plastic housing part swells as a result of the liquid fuel, or even as a result of fuel vapors, so that after a certain operating life optimum functioning of the elastomeric seal, which is merely seated in a circumferential groove of the housing, is no longer guaranteed when the closure flap is closed. As a result of the swelling of the plastic, the press-fit seating for the seal on the housing part is adversely affected.
The disadvantages of the prior art may be overcome by providing a filler pipe for a fuel tank of a motor vehicle comprising a tubular housing defining an aperture in fluid communication with the fuel tank. A closure flap is operatively coupled to the housing and operable between an open position opening the aperture for allowing fuel to fill the fuel tank and a closed position closing the aperture. An annular recess is formed in the tubular housing adjacent the aperture. An elastomeric seal is supported in the annular recess between the housing and the closure flap for providing a fluid impervious seal therebetween.
It is the object of the invention, which begins at this point, to provide a sealing concept which ensures a reliable and lasting sealing of the closure flap on the filling aperture in the event of any swelling of the plastic housing under the influence of fuel.
The stated object is achieved in part in that the seal is applied to a seal support which is connected to the plastic housing, the seal providing a seal both relative to the closure flap and relative to the housing part.
The effect of connecting a separate seal support to the housing part is to ensure that, even in the event of swelling of the plastic material of the housing, the seal is fixed in its position. The xe2x80x9cdouble-actionxe2x80x9d seal, which provides a seal both relative to the closure flap and relative to the housing, guarantees the necessary and desirable sealing of the closure flap over the service life of the filler pipe.
The seal support may be connected to the housing part by positive fitting or by mechanical fixing. Both measures ensure secure retention of the seal support which cannot be released during operation.
According to a preferred embodiment of the invention, the seal support together with the seal is retained in at least one recess formed in the housing part. This measure also assists the retention of the seal.
The seal itself is provided with two sealing parts, for example sealing beads or sealing lips, one sealing part being capable of being supported on the closure flap and the second on the base of the recess. This effectively favors the desired sealing effect.
The seal is preferably vulcanized or injected onto the seal support. As a result, the seal is permanently retained on the seal support.
For the positive-fitting connection of the seal support to the housing part, provision is made, in particular, for the seal support to be provided with one or more anchoring parts which are retained by positive fitting or mechanically fixed in the region of the recess. As a result, the seal support is anchored on the housing in a manner that is particularly secure and substantially uninfluenced by possible swelling of the plastic material.
In a preferred, particularly durable method of connecting the seal support to the housing part, a marginal region of the housing part is flanged onto the anchoring part, for example by means of ultrasound. As an alternative to this, the seal support can also be connected by screwing, welding, clipping, or the like.
Particularly advantageous is an embodiment in which the two sealing parts of the seal produce a sealing effect at least substantially in the axial direction, based on the longitudinal axis of the housing. As a result, possible swelling of the plastic of the housing can be particularly easily compensated for by elastic deformation of the seal.